1. Technical Field
In machine tools furnished with a moving body, a drive mechanism for driving the moving body so as to move it, and a structure placed in the region in which the moving body can travel, the present invention relates to machine tool controllers that control actuation of the drive mechanism.
2. Description of the Related Art
The moving body and the structure placed in the region where moving body travels are at risk of interfering with each other. Machine tool controllers to prevent such interference have been known to date; such devices include the machine tool numerical control device disclosed in Japanese Unexamined Pat. App. Pub. 2006-59187.
This numerical control device, which is configured to prevent interference between the moving body and the structure while the moving body is moved by means of a manual operation, is made up of: a function generating means that receives an operational signal, which concerns the manual operation and is input from a control panel, to generate functions for executing control of the moving body's travel; a three-dimensional data memory for storing geometry data on the moving body and on the structure could interfere with the moving body; and a interference-checking device that checks by moving the moving body whether or not it will interfere with the structure, based on the moving body's and the structure's geometry data stored in the three-dimensional data memory, before the function generator receives the operational signal concerning the manual operation to start generating a function, and when determining that interference would occur, calculates a stop position at a certain distance from the structure. When the interference-checking device determines that the moving body would interfere with the structure, the function generator discontinues function generation so that the moving body will stop at the stop position.
According to this numerical control device, the moving-body and structure geometry data is employed to check whether interference would occur, before generation of a function for moving the moving body is started, so that interference between the moving body and the structure is efficaciously prevented.
In actual practice with machine tools in situations in which an operator moves the moving body to a predetermined move-to point by a manual operation, the moving body is not moved at a high speed all the way to the move-to point, but usually is moved at a high speed to the vicinity of, and then at a gradually decreasing speed into, the move-to point, even if the machine tool is equipped with in interference prevention function. That is, the operator moves the moving body to the predetermined move-to point while controlling feedrate override, depending on the move-to point of the moving body, to adjust the moving speed of the moving body.
Moving the moving body along with controlling the feedrate override to adjust the moving speed, however, complicates work operations. Additionally, an operator, bearing in mind that the interference prevention function is for preventing interference, will be concerned that interference may occur, and may make the operational error of moving the moving body at a high speed near the structure.
Moreover, with one of the examples of an interference prevention function that has been proposed, based on the moving body actual position sent from the controller and on an interference region predetermined, as appropriate, as the region in which the moving body and the structure would interfere with each other, a check is made as to whether or not the moving body enters the interference region, and the moving body is stopped when the moving body is determined to enter the region. With such a function, if the interference region is defined to be narrow, however, the moving body is not immediately stopped when being moved at a high speed, and can interfere with the structure. On the other hand, if the interference region is defined to be wide in order to overcome such a disadvantage, the travel region is narrowed, compromising workability.
The present invention is directed to solving these problems, and an object of the invention is to make available a machine tool controller that enables an operator to work the moving body by means of simple and worry-free manual operation.